Magnetic shield, semiconductor device, and semiconductor package

ABSTRACT

Provided is a magnetic shield having improved shielding properties from an external magnetic field. A magnetic shield MS 1  has in-plane magnetization as remanent magnetization, and is adapted to generate a perpendicular component in the magnetization direction by applying a magnetic field in the perpendicular direction to the magnetic shield.

CROSS-REFERENCE TO RELATED APPLICATIONS

The disclosure of Japanese Patent Application No. 2013-132750 filed onJun. 25, 2013 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND

The present invention relates to magnetic shields, semiconductordevices, and semiconductor packages, and more particularly, to asemiconductor device including a magnetoresistive memory, and asemiconductor package therein.

Currently, a magnetoresistive memory (MRAM (magnetoresistive randomaccess memory) has been increasingly developed. Techniques regarding themagnetoresistive memory include, for example, those disclosed in PatentDocuments 1 to 3.

Patent Documents 1 and 2 relate to the technique about themagnetoresistive memory in which the direction of magnetization of afree layer is reversed using spin implantation. As disclosed in any oneof the above patent documents, the perpendicular anisotropy is appliedto the free layer. Patent Document 3 discloses a nonvolatile solid-statemagnetic memory device having a magnetic shield structure for shieldinga MRAM chip from an external scattered magnetic field.

RELATED ART DOCUMENTS Patent Documents

-   [Patent Document 1] Japanese Unexamined Patent Application    Publication (Translation of PCT Application) No. 2007-525847-   [Patent Document 2] U.S. Patent Application No. 2005/0104101-   [Patent Document 3] Japanese Unexamined Patent Publication No.    2003-115578

SUMMARY

Some magnetoresistive memories are covered by a magnetic shield so as tosuppress the influence of external magnetic field on themagnetoresistive memory. In such a magnetic shield, however, the changein magnetization in its perpendicular direction is interrupted by theinfluence of diamagnetic field acting in the thickness direction of themagnetic shield, which could make it difficult to achieve a sufficientmagnetic permeability with respect to the external magnetic field in theperpendicular direction. In this case, the magnetic shield hardlyachieves the sufficient shielding properties from the perpendicularexternal magnetic field.

Other problems and new features of the present invention will beclarified in the following detailed description in connection with theaccompanying drawings.

According to one embodiment of the invention, a magnetic shield has thein-plane magnetization as remanent magnetization, and the perpendicularmagnetic anisotropy is imparted to the magnetic shield.

In the one embodiment of the invention, the magnetic shield can improveits shielding properties from the external magnetic field.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary cross-sectional view showing a magnetoresistivememory and a magnetic shield in one embodiment of the invention;

FIG. 2 is an exemplary cross-sectional view for explaining the change inmagnetization within the magnetic shield;

FIG. 3 is a graph exemplarily showing the relationship between theperpendicular external magnetic field, and a perpendicular magnetizationcomponent generated in the magnetic shield by the external magneticfield;

FIG. 4 is an exemplary cross-sectional view showing one example of themagnetic shield in the one embodiment;

FIGS. 5A and 5B are exemplary cross-sectional views showing modifiedexamples of the magnetic shield shown in FIG. 4;

FIGS. 6A and 6B are exemplary cross-sectional views showing asemiconductor device in the one embodiment;

FIG. 7 is an exemplary cross-sectional view showing a semiconductorpackage in the one embodiment;

FIG. 8 is an exemplary plan view showing the positional relationshipbetween a semiconductor chip and the magnetic shield in thesemiconductor package shown in FIG. 7; and

FIG. 9 is an exemplary cross-sectional view showing a modified exampleof the semiconductor package shown in FIG. 7.

DETAILED DESCRIPTION

In the following, preferred embodiments of the present invention will bedescribed with reference to the accompanying drawings. Whereverpossible, the same reference numerals will be used through the drawingsto refer to the same or like parts, and thus a description thereof willbe omitted below.

FIG. 1 is an exemplary cross-sectional view of a magnetoresistive memoryMM1 and a magnetic shield MS1 in one embodiment of the invention. FIG. 1exemplarily shows the positional relationship between themagnetoresistive memory MM1 and the magnetic shield MS1.

The magnetic shield MS1 of this embodiment has the in-planemagnetization as remanent magnetization. By applying a magnetic field inthe perpendicular direction, the magnetic shield MS1 generates aperpendicular component in the magnetization direction. As to themagnetization direction of the magnetic shield MS1 and the externalmagnetic field applied to the magnetic shield MS1, the term“perpendicular direction” as used herein means the directionperpendicular to (perpendicularly shown in FIG. 1) the film surface ofthe magnetic shield MS1, and the term “in-plane direction” as usedherein means the direction parallel to the film surface of the magneticshield MS1. The same goes for a magnetic recording layer MR1 and amagnetic reference layer RL1 to be described later.

In this embodiment, the perpendicular magnetic anisotropy is imparted tothe magnetic shield MS1 having the in-plane magnetization as theremanent magnetization. In this case, the diamagnetic field acting onthe magnetic shield MS1 in the thickness direction cancels theperpendicular magnetic anisotropy imparted to the magnetic shield MS1.Thus, by applying the external magnetic field to the magnetic shield MS1in the perpendicular direction, the magnetic shield MS1 generates aperpendicular component in the magnetization direction. That is, themagnetic shield MS1 tends to cause a change in magnetization due to theexternal magnetic field in the perpendicular direction, and thus canachieve the sufficient magnetic permeability of the external magneticfield in the perpendicular direction. Thus, the magnetic shield canimprove its shielding properties from the external magnetic field in theperpendicular direction.

The following will refer to the details of the structure of the magneticshield MS1, a semiconductor device SD1 including the magnetic shieldMS1, and the structure of a semiconductor package SP1 in thisembodiment.

First, the structure of the magnetic shield MS1 will be described below.

The magnetic shield MS1 is disposed in the vicinity of themagnetoresistive memory MM1, and has a function of suppressing theinfluence of the external magnetic field on the magnetoresistive memoryMM1. The magnetic shield MS1 is disposed spaced apart from themagnetoresistive memory MM1.

The magnetic shield MS1 of this embodiment can be formed in a flatplate-like shape having a thickness, for example, of not less 1 μm normore than 10 μm, or in a thin film-like shape having a thickness of notless than 1 nm nor more than 30 nm. The flat plate-like magnetic shieldMS1 is provided above or under the semiconductor chip including, forexample, the magnetoresistive memory MM1. The magnetic shield MS1 in theform of thin film is provided, for example, above or under themagnetoresistive memory MM1 within the semiconductor chip.

In the example shown in the exemplary cross-sectional view of FIG. 1,the magnetic shields MS1 are respectively provided above and under themagnetoresistive memory MM1. Alternatively, the magnetic shield MS1 maybe provided above or under the magnetoresistive memory MM1.

The magnetic shield MS1 is preferably provided to be superimposed overthe entire magnetoresistive memory MM1 in the planar view. Thisstructure can more effectively suppress the influences of the externalmagnetic field on the magnetoresistive memory MM1. In this embodiment,for example, the magnetic shield MS1 is provided to cover the entiremagnetoresistive memories MM1 arranged in an array.

The magnetic shield MS1 has the in-plane magnetization as the remanentmagnetization. By applying a magnetic field in the perpendiculardirection, the magnetic shield MS1 generates a perpendicular componentin the magnetization direction of the magnetic shield MS1. As to themagnetization direction of the magnetic shield MS1 and the externalmagnetic field applied to the magnetic shield MS1, the term“perpendicular direction” as used herein means the directionperpendicular to the film surface of the magnetic shield MS1. That is,the perpendicular direction is identical to the film thickness directionof the flat plate-like or thin film-like magnetic shield MS1. Thein-plane direction is identical to the plane direction with theperpendicular direction set as the direction of a normal line.

FIG. 2 is an exemplary cross-sectional view for explaining the change inmagnetization within the magnetic shield MS1.

When the external magnetic field is applied in the perpendiculardirection to the flat plate-like or thin-film-like magnetic shield,polarization will occur at each of the upper and lower surfaces of themagnetic shield. The change in magnetization of the magnetic shield inthe perpendicular direction is interrupted by the diamagnetic fieldgenerated in the magnetic shield by the polarization. In this case, itbecomes difficult to obtain the sufficient magnetic permeability for theperpendicular external magnetic field.

The perpendicular magnetic anisotropy is imparted to the magnetic shieldMS1 of this embodiment, so that the perpendicular magnetic anisotropycancels the diamagnetic field. Thus, as shown in FIG. 2, themagnetization direction of the magnetic shield MS1 can easily changeinto the perpendicular direction. That is, the magnetic shield MS1 canachieve the high magnetic permeability for the external magnetic fieldin the perpendicular direction. Thus, a magnetic flux generated by theperpendicular external magnetic field can be effectively absorbed in themagnetic shield MS1. The magnetic shield MS1 has the in-planemagnetization as the remanent magnetization, so that the magnetic fluxcaused by the absorbed external magnetic field flows obliquely withrespect to the perpendicular direction of the magnetic shield MS1. As aresult, the density of magnetic flux around the magnetoresistive memoryMM1 can be reduced. In this embodiment, for example, in the waydescribed above, the magnetic shield MS1 can suppress the influence ofthe perpendicular external magnetic field on the magnetoresistive memoryMM1.

Further, the magnetic shield MS1 of this embodiment can also achieve thehigh magnetic permeability for the external magnetic field in thein-plane direction because of the presence of the in-planemagnetization. Therefore, this embodiment can suppress the influence ofthe in-plane external magnetic field on the magnetoresistive memory MM1,using the magnetic shield MS1.

FIG. 3 is a graph exemplarily showing the relationship between theperpendicular external magnetic field applied to the magnetic shieldMS1, and a perpendicular magnetization component generated in themagnetic shield by the external magnetic field. This figure shows amagnetization curve in which a horizontal axis indicates an externalmagnetic field H in the perpendicular direction, and a longitudinal axisindicates the perpendicular magnetization M generated in the magneticshield MS1.

Like the magnetization curve shown in FIG. 3, by applying theperpendicular external magnetic field H to the magnetic shield MS1, theperpendicular magnetization M is generated within the magnetic shieldMS1. The inclination of the magnetization curve can be adjusted tocontrol the magnetic permeability of the magnetic shield MS1 withrespect to the perpendicular external magnetic field. The inclination ofthe magnetization curve can be controlled by appropriately adjusting thematerial, structure, and formation conditions for forming the magneticshield MS1.

In this embodiment, for example, 4πM_(s) is a saturated magnetizationgenerated when a perpendicular external magnetic field Hk_(eff) isapplied to the magnetic shield MS1. In this case, the following formulais preferably satisfied: 5≦4πM_(s)/Hk_(eff)≦20. This arrangement canachieve the sufficient magnetic permeability for the perpendicularexternal magnetic field, thereby effectively suppressing the influencesof the external magnetic field in the perpendicular direction on themagnetoresistive memory MM1. The value 4πM_(s)/Hk_(eff) corresponds toan effective magnetic permeability μ of the magnetic shield MS1.

In this embodiment, the perpendicular magnetization generated in themagnetic shield MS1 by applying the external magnetic field in theperpendicular direction is controlled not to exceed the diamagneticfield that can be generated in the thickness direction (perpendiculardirection) of the magnetic shield MS1. This arrangement can suppress theproblem of loss of the shielding properties from the perpendicularexternal magnetic field due to the conversion of the magnetizationdirection of the magnetic shield MS1 into the completely perpendiculardirection. The perpendicular magnetization generated in the magneticshield MS1 can be controlled by respectively adjusting the material,structure, and formation conditions for forming the magnetic shield MS1.The diamagnetic field generated in the film thickness direction of themagnetic shield MS1 can be controlled by respectively adjusting theshape or film thickness of the magnetic shield MS1.

FIG. 4 shows an exemplary cross-sectional view of one example of themagnetic shield in the one embodiment.

In the magnetic shield MS1 of this embodiment, the magnetizationcomponent in the perpendicular direction which is generated by theperpendicular external magnetic field applied to the magnetic shield MS1can be actually generated, for example, by using an interface magneticanisotropy.

In this embodiment, as shown in FIG. 4, for example, a magnetic layerML1 having the in-plane magnetic anisotropy and a non-magnetic layer NM1inducing the interface magnetic anisotropy with the magnetic layer ML1are stacked each other to form a laminated film, which can form themagnetic shield MS1. Thus, the perpendicular magnetic anisotropy isimparted to the magnetic shield MS1 by the interface magneticanisotropy.

The magnetic layer ML1 is formed of, for example, CoFeB, CoFe, NiFe, orNiFeCo. The non-magnetic layer NM1 is formed of, for example, an oxidefilm made of MgO or the like, or a non-magnetic metal film made of Ta orPt. This arrangement can effectively induce the interface magneticanisotropy between the magnetic layer ML1 and the non-magnetic layerNM1. In this embodiment, a combination of the magnetic layer ML1 made ofCoFeB and the non-magnetic layer NM1 made of MgO can be taken as anexample.

Alternatively, this embodiment can have a three-layered structureincluding the non-magnetic layer NM1, the magnetic layer ML1, and thenon-magnetic layer NM1 which are laminated in that order, or a laminatedfilm composed of a three-layered structure including the magnetic layerML1, the non-magnetic layer NM1, and the magnetic layer ML1 which arelaminated in that order.

FIGS. 5A and 5B show exemplary cross-sectional views of modifiedexamples of the magnetic shield shown in FIG. 4.

Referring to FIG. 5A, the laminated film forming the magnetic shield MS1includes a plurality of magnetic layers ML1 and a plurality ofnon-magnetic layers NM1 which are alternately stacked, by way ofexample. In this case, at each interface between the magnetic layer ML1and the non-magnetic layer NM1, the interface magnetic anisotropy isinduced. Thus, the number of the magnetic layers ML1 and thenon-magnetic layers NM1 can be adjusted to control the magneticpermeability of the magnetic shield MS1 with respect to theperpendicular external magnetic field.

FIG. 5B exemplifies the addition of a magnetic layer ML2 and anintermediate layer IL1. The magnetic layer ML2 has the in-plane magneticanisotropy. The intermediate layer IL1 is provided between the magneticlayer ML2 and the above-mentioned laminated film of the magnetic layerML1 and the non-magnetic layer NM1. The intermediate layer IL1 is alayer that does not induce the interface magnetic anisotropy with themagnetic layer ML2. In this case, the magnetic shield MS1 can improveits magnetic permeability for the in-plane external magnetic field.Thus, the magnetic shield MS1 can be achieved which has the excellentshielding effect from the external magnetic field in both the in-planedirection and the perpendicular direction.

The magnetic layer ML2 is formed of, for example, NiFe. Thus, themagnetic permeability of the magnetic shield MS1 from the in-planeexternal magnetic field can be efficiently improved. The intermediatelayer IL1 is formed of, for example, Ta. Thus, the intermediate layerIL1 can prevent the interface magnetic anisotropy from being inducedwith the magnetic layer ML2 to stably control the magnetic permeabilityof the magnetic shield MS1.

In the magnetic shield MS1 of this embodiment, for example, theperpendicular magnetic anisotropy imparted to the magnetic shield MS1can also be generated by use of a crystal magnetic anisotropy. In thiscase, the magnetic shield MS1 is formed of, for example, CoPt. Thus, theperpendicular magnetic anisotropy is imparted to the magnetic shield MS1by the crystal magnetic anisotropy.

In the magnetic shield MS1 of this embodiment, for example, theperpendicular magnetic anisotropy imparted to the magnetic shield MS1can also be generated by use of the strain magnetic anisotropy. In thiscase, the magnetic shield MS1 is formed of, for example, a Ni/Culaminated film. Thus, the perpendicular magnetic anisotropy is impartedto the magnetic shield MS1 by the strain magnetic anisotropy.

The magnetoresistive memory MM1 protected by the magnetic shield MS1includes a laminate of, for example, the magnetic reference layer RL1, atunnel barrier layer TB1, and a magnetic recording layer MR1. Themagnetic reference layer RL1 and the magnetic recording layer MR1 are amagnetic layer formed of ferromagnetic material. The tunnel barrierlayer TB1 is a non-magnetic layer formed of non-magnetic material. Thelaminated structure of the magnetic reference layer RL1, the tunnelbarrier layer TB1, and the magnetic recording layer MR1 forms a magnetictunnel junction MTJ.

The magnetic shield MS1 is provided above or under the magnetoresistivememory MM1. As shown in FIG. 1, the flat plate-like or thin film-likemagnetic shield MS1 is disposed in parallel to a plane having thelamination direction of the magnetic reference layer RL1, the tunnelbarrier layer TB1, and the magnetic recording layer MR1 as a normalline. In this case, the magnetoresistive memories MM1 arranged in anarray can be effectively covered. In particular, the thin film-likemagnetic shield MS1 can be formed in a wiring layer forming a multilayerinterconnection structure within the semiconductor chip.

In this embodiment, the magnetic recording layer MR1 and the magneticreference layer RL1 included in the magnetoresistive memory MM1 have,for example, a perpendicular magnetic anisotropy. In this case, themagnetic recording layer MR1 and the magnetic reference layer RL1 areformed of, for example, a ferromagnetic material with a perpendicularmagnetic anisotropy. The term “perpendicular magnetic anisotropy”indicates a magnetic anisotropy in which the direction perpendicular tothe film surface of each layer becomes the magnetization easy axis.

The magnetic recording layer MR1 having the perpendicular magneticanisotropy tends to be affected by the external magnetic field in theperpendicular direction. In this embodiment, however, themagnetoresistive memory MM1 can be covered by the magnetic shield MS1with excellent shielding properties from the perpendicular externalmagnetic field. Thus, the magnetic shield MS1 can suppress the influenceof the perpendicular external magnetic field on the magnetic recordinglayer MR1. Accordingly, the magnetoresistive memory MM1 including themagnetic recording layer MR1 with a perpendicular magnetic anisotropycan have the good operating performance.

The magnetic recording layer MR1 and the magnetic reference layer RL1included in the magnetoresistive memory MM1 may have, for example, thein-plane magnetic anisotropy. In this case, the magnetic recording layerMR1 and the magnetic reference layer RL1 are formed of a ferromagneticmaterial having, for example, the in-plane magnetic anisotropy. The term“in-plane magnetic anisotropy” indicates a magnetic anisotropy in whichthe direction parallel to the film surface of each layer becomes themagnetization easy axis.

The magnetoresistive memory MM1 writes the data “1” or “0” by reversingthe magnetization of the magnetic recording layer MR1. Methods forreversing the magnetization of the magnetic recording layer MR1 are notspecifically limited, but can include, for example, a current magneticfield process, a spin injection process, and a domain wall displacementprocess. In the current magnetic field process, a magnetic field isgenerated by current flowing through a wiring provided around themagnetic tunnel junction MTJ, thereby reversing the magnetization of themagnetic recording layer MR1. In the spin injection process, a currentis allowed to flow in such a direction as to pass through the magnetictunnel junction MTJ, whereby the spin-polarized current is used in themagnetic reference layer RL1 to reverse the magnetization of themagnetic recording layer MR1. In the domain wall displacement process, adomain wall in the magnetic recording layer MR1 is moved by a currentapplied to the inside of the magnetic recording layer MR1, therebyreversing the magnetization.

A reading operation of the magnetoresistive memory MM1 is performed byallowing a current for reading to flow in such a direction as topenetrate the magnetic tunnel junction MTJ. In this way, a resistancevalue of the magnetic tunnel junction MTJ is detected, so that data “0”or “1” corresponding to the resistance value is read out.

When the magnetization direction of the magnetic recording layer MR1 isantiparallel to the magnetization direction of the magnetic referencelayer RL1, the resistance value of the magnetic tunnel junction MTJbecomes relatively higher. In contrast, when the magnetization directionof the magnetic recording layer MR1 is the same as the magnetizationdirection of the magnetic reference layer RL1, the resistance value ofthe magnetic tunnel junction MTJ becomes relatively lower. Theseresistance values respectively correspond to either the data “1” or “0”.

Now, the semiconductor device SD1 of this embodiment will be described.

FIG. 6 is an exemplary cross-sectional view showing the semiconductordevice SD1 in this embodiment. FIG. 6A shows the structure of thesemiconductor device SD1 at one cross section. FIG. 6B shows thestructure of the semiconductor device SD1 at another cross sectionperpendicular to the one cross section shown in FIG. 6A.

The semiconductor device SD1 includes the magnetoresistive memory MM1,and the magnetic shield MS1 provided above or under the magnetoresistivememory MM1. The magnetic shield MS1 and the magnetoresistive memory MM1as described above can be used. FIG. 6 shows an example in which themagnetic shield MS1 is provided above the magnetoresistive memory MM1.

In the example shown in FIG. 6, the magnetoresistive memory MM1 and themagnetic shield MS1 can be formed within the semiconductor chip. Thus,in a post-process, a step of forming the magnetic shield MS1 can beomitted.

The semiconductor device SD1 of this embodiment includes a semiconductorsubstrate SB1, and a transistor TR1 provided at the semiconductorsubstrate SB1. The semiconductor substrate SB1 is not specificallylimited, but is, for example, a silicon substrate or a compoundsemiconductor substrate. As shown in FIGS. 6A and 6B, the transistor TR1includes, for example, a gate insulating film GI1 provided over asemiconductor substrate SB1, a gate electrode GE1 provided over the gateinsulating film GI1, sidewalls SW1 provided over the sides of the gateelectrode GE1, and source and drain regions DR1 provided at thesemiconductor substrate SB1 so as to sandwich the gate electrode GE1 inthe planar view. FIG. 6 shows the case where a plurality of transistorsTR1 are provided at the semiconductor substrate SB1. An elementisolation film EI1 is embedded in the semiconductor substrate SB1 suchthat the transistors TR1 are separated from each other and from otherelements.

An interlayer insulating film II1 is provided over the semiconductorsubstrate SB1 to cover the transistor TR1. A contact plug CP1 to becoupled to the source and drain regions DR1 is embedded in theinterlayer insulating film II1.

The magnetoresistive memory MM1 is provided over the interlayerinsulating film II1. The magnetoresistive memory MM1 includes, forexample, the magnetic reference layer RL1 provided over the interlayerinsulating film II1, the tunnel barrier layer TB1 provided over themagnetic reference layer RL1, and the magnetic recording layer MR1provided over the tunnel barrier layer TB1. At this time, the magneticreference layer RL1 is coupled to the source and drain regions DR1, forexample, via the contact plug CP1. The magnetoresistive memory MM1 isformed, for example, in the interlayer insulating film II2. Thestructure of the magnetoresistive memory MM1 is not limited thereto, andcan be formed in an arbitrary wiring layer in the multilayerinterconnection structure.

In this embodiment, the magnetic recording layer MR1 and the magneticreference layer RL1 included in the magnetoresistive memory MM1 have,for example, a perpendicular magnetic anisotropy. On the other hand, asdescribed later, the magnetic shield MS1 is provided above themagnetoresistive memory MM1 to cover the magnetoresistive memory MM1.The magnetic shield MS1 has good shielding properties from theperpendicular external magnetic field. Thus, the magnetic shield MS1 canreduce the influences of the perpendicular external magnetic field onthe magnetic recording layer MR1. The magnetic recording layer MR1 andthe magnetic reference layer RL1 included in the magnetoresistive memoryMM1 may have, for example, the in-plane magnetic anisotropy.

Referring to FIG. 6, the plural magnetoresistive memories MM1 areprovided by way of example. In this example, the magnetoresistive memoryMM1 are provided, for example, to be coupled to the respective sourceand drain regions DR1 of the different transistors TR1. In thesemiconductor device SD1 of this embodiment, the magnetoresistivememories MM1 arranged in an array are preferably formed.

An interlayer insulating film II3 with a bit line BL1 embedded thereinis provided over the interlayer insulating film II2. The bit line BL1 iscoupled, for example, to the magnetic recording layer MR1. As shown inFIG. 6, one bit line BL1 is coupled to the magnetoresistive memories MM1by way of example. An interlayer insulating film II4 is provided overthe interlayer insulating film II3.

The magnetic shield MS1 is provided over the interlayer insulating filmII4. An interlayer insulating film II5 is provided over the interlayerinsulating film II4 to cover the magnetic shield MS1.

The magnetic shield MS1 is disposed above the magnetoresistive memoryMM1 to cover the magnetoresistive memory MM1. That is, the magneticshield MS1 is provided above the magnetoresistive memory MM1 via aninsulating layer. Thus, the magnetic shield MS1 and the magnetoresistivememory MM1 are electrically isolated from each other.

The magnetic shield MS1 has, for example, a thin-film like shape of notless than 1 nm nor more than 30 nm in thickness. As shown in FIG. 6, themagnetic shield MS1 is provided to cover the magnetoresistive memoriesMM1 by way of example. In this embodiment, for example, themagnetoresistive memory MM1 can be provided such that a cell arrayincluding the magnetoresistive memories MM1 arranged in an array iscovered as a whole. Alternatively, the magnetic shield MS1 may be formedin a wiring layer positioned under the magnetoresistive memory MM1.

Next, the semiconductor package SP1 of this embodiment will bedescribed.

FIG. 7 shows an exemplary cross-sectional view of the semiconductorpackage SP1 in the one embodiment. FIG. 8 shows an exemplary plan viewof the positional relationship between the semiconductor chip SC1 andthe magnetic shield MS1 in the semiconductor package SP1 shown in FIG.7. A broken line in FIG. 8 indicates a position of a region where amemory cell array CA1 is formed.

The semiconductor package SP1 includes the semiconductor chip SC1 havingthe magnetoresistive memory MM1, and the magnetic shield MS1 providedabove or under of the semiconductor chip SC1. The magnetic shield MS1and the magnetoresistive memory MM1 can be formed using theabove-mentioned ones. FIG. 7 shows the example in which the magneticshield MS1 is provided above the semiconductor chip SC1.

The semiconductor package SP1 of this embodiment includes, for example,a lead frame LF1. The lead frame LF1 includes a die pad DP1, and anouter lead OL1 provided around the die pad DP1.

The semiconductor chip SC1 is mounted over the die pad DP1 via a dieattach layer DA1. The outer lead OL1 and an electrode pad (not shown)formed above the upper surface of the semiconductor chip SC1 are coupledtogether, for example, via bonding wires BW1.

The magnetic shield MS1 has, for example, a flat plate-like shape of notless than 1 μm nor more than 10 μm in thickness. Referring to FIG. 7,the magnetic shield MS1 is provided over the semiconductor chip SC1 viaa die attach layer DA2 by way of example.

As shown in FIG. 8, for example, the magnetic shield MS1 provided overthe semiconductor chip SC1 is smaller than that of the semiconductorchip SC1 in the planar view. That is, a visible outline of the magneticshield MS1 in the planar view is positioned inside a visible outline ofthe semiconductor chip SC1 in the planar view. Thus, the electrode padprovided at the outer periphery of the semiconductor chip SC1 forcoupling the bonding wire BW1 can be exposed.

A memory cell array CA1 is provided in the semiconductor chip SC1. Thememory cell array CA1 is comprised of, for example, a plurality ofmagnetoresistive memories MM1. The magnetic shield MS1 is provided overthe semiconductor chip SC1 so as to cover the entire memory array CA1 inthe planar view.

In this embodiment, the magnetic recording layer MR1 and the magneticreference layer RL1 included in the magnetoresistive memory MM1 have,for example, a perpendicular magnetic anisotropy. The magnetic shieldMS1 which has the good shielding properties from the perpendicularexternal magnetic field is provided over the semiconductor chip SC1 tocover the magnetoresistive memory MM1. Thus, the magnetic shield MS1 cansuppress the influence of the external magnetic field in theperpendicular direction for the magnetic recording layer MR1. Themagnetic recording layer MR1 and the magnetic reference layer RL1included in the magnetoresistive memory MM1 may have, for example, thein-plane magnetic anisotropy.

The semiconductor package SP1 is provided with a sealing resin ER1 forsealing therein the semiconductor chip SC1 and the magnetic shield MS1.

The structure of the semiconductor package SP1 is not limited to theabove. The semiconductor package SP1 may be formed, for example, bymounting the semiconductor chip SC1 over a wiring board via a bump. Alsoin this case, the magnetic shield MS1 can be disposed over thesemiconductor chip SC1 via the die attach layer DA2.

FIG. 9 shows an exemplary cross-sectional view of a modified example ofthe semiconductor package SP1 shown in FIG. 7.

In the semiconductor package SP1 of the modified example, the magneticshields MS1 are respectively provided above and under a semiconductorchip SC1. This arrangement can effectively suppress the influence of theexternal magnetic field on the magnetoresistive memory MM1.

As shown in FIG. 9, a magnetic shield MS12 (MS1) is provided over thedie pad DP1 via a die attach layer DA3. The semiconductor chip SC1 isprovided over the magnetic shield MS12 via the die attach layer DA1. Amagnetic shield MS11 (MS1) is provided over the semiconductor chip SC1via a die attach layer DA2.

In the modified example, the magnetic shield MS12 can be provided to belarger than the semiconductor chip SC1 in the planar view. At this time,a visible outline of the magnetic shield MS12 in the planar view ispositioned outside a visible outline of the semiconductor chip SC1 inthe planar view. This arrangement can more effectively suppress theinfluence on the magnetoresistive memory MM1 by the external magneticfield generated under the semiconductor chip SC1.

In contrast, the magnetic shied MS11 is provided, for example, to besmaller than the semiconductor chip SC1 in the planer view. That is, avisible outline of the magnetic shield MS11 in the planar view ispositioned inside a visible outline of the semiconductor chip SC1 in theplanar view. Thus, the electrode pad can be exposed to be provided atthe outer periphery of the semiconductor chip SC1 and adapted to couplethe bonding wires BW1.

Next, the effects of the preferred embodiments of the invention will bedescribed.

In the embodiments of the invention, the perpendicular magneticanisotropy is imparted to the magnetic shield having the in-planemagnetization as the remanent magnetization. In this case, thediamagnetic field acting on the magnetic shield MS1 in the filmthickness direction cancels the perpendicular magnetic anisotropyimparted to the magnetic shield MS1. Thus, by applying the externalmagnetic field to the magnetic shield MS1 in the perpendiculardirection, the magnetic shield MS1 generates a perpendicular componentin the magnetization direction. That is, the magnetic shield MS1 tendsto cause a change in magnetization due to the external magnetic field inthe perpendicular direction, and thus can achieve the sufficientmagnetic permeability of the external magnetic field in theperpendicular direction. Thus, the magnetic shield MS1 can improve itsshielding properties from the external magnetic field in theperpendicular direction.

In this way, the magnetic shield of the one embodiment can improve itsshielding properties from the external magnetic field.

The invention made by the inventors has been specifically describedbased on the embodiments. However, it is apparent that the invention isnot limited to the embodiments described above, and that variousmodifications and changes can be made without departing from the scopeof the invention.

What is claimed is:
 1. A magnetic shield having magnetization in an in-plane direction as remanent magnetization, wherein the magnetic shield is adapted to generate a perpendicular component in a magnetization direction by applying a magnetic field thereto in a perpendicular direction.
 2. The magnetic shield according to claim 1, wherein when 4πM_(s) is a perpendicular saturated magnetization generated by an external magnetic field Hk_(eff) in the perpendicular direction, the following formula is satisfied: 5≦4πM_(s)/Hk_(eff)≦20.
 3. The magnetic shield according to claim 1, wherein the magnetic shield includes a laminated film having a first magnetic layer having in-plane magnetic anisotropy, and a non-magnetic layer inducing interface magnetic anisotropy with respect to the first magnetic layer.
 4. The magnetic shield according to claim 3, wherein the first magnetic layer is formed of CoFeB, CoFe, NiFe, or NiFeCo, and wherein the non-magnetic layer is formed of MgO, Ta, or Pt.
 5. The magnetic shield according to claim 3, wherein the laminated film includes a plurality of the first magnetic layers and a plurality of the non-magnetic layers which are alternately stacked on each other.
 6. The magnetic shield according to claim 3, further comprising: a second magnetic layer having in-plane magnetic anisotropy; and an intermediate layer provided between the second magnetic layer and the laminated film, the intermediate layer being adapted not to induce interface magnetic anisotropy with respect to the second magnetic layer.
 7. The magnetic shield according to claim 6, wherein the second magnetic layer is formed of NiFe, and the intermediate layer is formed of Ta.
 8. The magnetic shield according to claim 1, wherein the perpendicular magnetization component is generated by crystal magnetic anisotropy.
 9. The magnetic shield according to claim 1, wherein the perpendicular magnetization component is generated by strain magnetic anisotropy.
 10. The magnetic shield according to claim 1, wherein the magnetic shield is formed in a flat plate-like or thin film-like shape.
 11. A semiconductor device, comprising: a magnetoresistive memory including a magnetic recording layer, a tunnel barrier layer, and a magnetic reference layer which are stacked on each other; and a magnetic shield provided above or under the magnetoresistive memory, wherein the magnetic shield has magnetization in an in-plane direction as remanent magnetization, and is adapted to generate a perpendicular component in a magnetization direction of the magnetic shield by applying a magnetic field thereto in a perpendicular direction.
 12. The semiconductor device according to claim 11, wherein the magnetic recording layer has perpendicular magnetic anisotropy.
 13. The semiconductor device according to claim 11, wherein the magnetic shield is provided above the magnetoresistive memory via an insulating layer.
 14. A semiconductor package, comprising: a semiconductor chip having a magnetoresistive memory; and a magnetic shield provided above or under the semiconductor chip, wherein the magnetic shield has magnetization in an in-plane direction as remanent magnetization, and is adapted to generate a perpendicular component in a magnetization direction of the magnetic shield by applying a magnetic field thereto in a perpendicular direction.
 15. The semiconductor package according to claim 14, wherein the magnetoresistive memory includes a magnetic recording layer having perpendicular magnetic anisotropy.
 16. The semiconductor package according to claim 14, wherein the magnetic shields are respectively provided above and under the semiconductor chip. 